1. Field of the Invention
This invention relates to linear, branched, and/or cross-linked block copolymers of polyphenylene oxides and polystyrenes. The polyphenylene oxide/polystyrene block copolymers can be molded, calendered or extruded as films, sheets, fibers, laminates or other useful articles of manufacture.
2. Description of the Prior Art
Self-condensation reactions of certain phenols employing oxygen in combination with an effective oxidative coupling catalyst system to form monofunctional prior art polyphenylene oxides, i.e., polyphenylene oxides having an average hydroxyl group per molecule of 1.0 or less are well known and are described in various publications including U.S. Pat. Nos. 3,306,875; 3,914,266; 4,028,341 to Hay, U.S. Pat. Nos. 3,956,442; 3,965,069; 3,972,851 and 4,052,553 to Olander.
U.S. Pat. No. 4,154,771 Loucks et al discloses a process of forming phosphorus containing block polymers of polyphenylene oxide.
U.S. Pat. No. 4,156,699 White discloses phosphorus containing block polymers of polyphenylene oxide formed using a phosphoryl halide.
U.S. Pat. No. 4,221,881 White discloses block copolymers of polyphenylene oxide and polystyrene formed using polyacyl halides as coupling agents.
U.S. Pat. No. 4,238,584 White discloses block copolymers of polyphenylene oxide and polystyrene formed using bis(haloformates) as coupling agents.
The polymeric product of the present invention differs from those in the above patents in what is sufficiently branched so as to form a gel which is composed of two different polymeric precursors.
The present process uses a liquid coupling agent as opposed to a solid coupling agent as disclosed in U.S. Pat. Nos. 4,238,381, 4,226,951 and 4,221,881. With a solid coupling agent, the rate of dissolution of the coupling agent substantially controls the rate of addition of reactant which means the solid can be added at once and in excess and still give quantitative coupling. With a liquid or a solution of coupling reagent, the reagent must be added at a carefully controlled rate to prevent an excess of reagent building up before all phenolic end groups have reacted.